In recent years, as homes and buildings are increasingly built air-tight, more and more people have been seeking healthy and comfortable life by removing airborne germs that are hazardous to human health from the air. In response to this trend, there have been developed many air purifiers fitted with various types of filter.
However, these air purifiers work by sucking the air in and then filtering it so that contaminants are absorbed or decomposed. Thus, as such air purifiers are used for an extended period, they imperatively requires maintenance, such as the exchanging of filters. Moreover, such air purifiers do not offer satisfactory performance because of their insufficient filtering characteristics.
On the other hand, there have also been developed air purifiers and air conditioners that work by increasing the ion concentration in the air by the use of an ion generating apparatus. However, the models that have been put on the market to date is of a type that generates negative ions alone. Although negative ions are expected to have some effect of relaxing humans, they have been found to have almost no effect of actively removing airborne germs from the air.
Moreover, conventional ion generating apparatus rely on a direct-current high-voltage system or pulse high-voltage system to generate and discharge negative ions from a sparkling needle. Thus, these ion generating apparatus require a high voltage of 5 kV or higher. This causes dust to collect in large amounts on a product incorporating such an ion generating apparatus and on an appliance or other object placed nearby. Moreover, to secure satisfactory safety against the use of a high voltage, such a product needs to be provided with some safety measure, as by being equipped with a safety circuit.